package sz.szsmk.citizencard.util;

import org.bouncycastle.jce.provider.BouncyCastleProvider;
import org.bouncycastle.pqc.math.linearalgebra.ByteUtils;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;
import java.io.UnsupportedEncodingException;
import java.security.Key;
import java.security.Security;
import java.util.Arrays;

public class Sm4Util {

    /**
     * sm4加密算法工具类
     * @explain sm4加密、解密与加密结果验证
     *          可逆算法
     * @version 1.0
     */

    static {
        Security.addProvider(new BouncyCastleProvider());
    }

    private static final String ENCODING = "UTF-8";
    public static final String ALGORITHM_NAME = "SM4";
    // 加密算法/分组加密模式/分组填充方式
    // PKCS5Padding-以8个字节为一组进行分组加密
    // 定义分组加密模式使用：PKCS5Padding
    public static final String ALGORITHM_NAME_ECB_PADDING = "SM4/ECB/PKCS5Padding";
    // 128-32位16进制；256-64位16进制
    public static final int DEFAULT_KEY_SIZE = 128;
    // 加密后前缀
    public static final String ENCRYPT_FLAG = "ENC2020-";
    // 密钥
    public static final String KEY = "4BF601E10C6D4DF3A53F67647991C6F0";


    /**
     * 生成ECB暗号
     * @explain ECB模式（电子密码本模式：Electronic codebook）
     * @param algorithmName
     *            算法名称
     * @param mode
     *            模式
     * @param key
     * @return
     * @throws Exception
     */
    private static Cipher generateEcbCipher(String algorithmName, int mode, byte[] key) throws Exception {
//        Cipher cipher = Cipher.getInstance(algorithmName, BouncyCastleProvider.PROVIDER_NAME);
        Cipher cipher = Cipher.getInstance(algorithmName,new BouncyCastleProvider());
        Key sm4Key = new SecretKeySpec(key, ALGORITHM_NAME);
        cipher.init(mode, sm4Key);
        return cipher;
    }

    /**
     * sm4加密
     * @explain 加密模式：ECB
     *          密文长度不固定，会随着被加密字符串长度的变化而变化
     * //@param hexKey
     *            16进制密钥（忽略大小写）
     * @param paramStr
     *            待加密字符串
     * @return 返回16进制的加密字符串
     * @throws Exception
     */
    public static String encryptEcb(String paramStr) {

//        Long a = System.currentTimeMillis();

        // 16进制字符串-->byte[]
        if (paramStr != null && !"".equals(paramStr.trim()) && !paramStr.startsWith(ENCRYPT_FLAG))
        {
            String cipherText = "";
            byte[] keyData = ByteUtils.fromHexString(KEY);
            // String-->byte[]
            byte[] srcData = new byte[0];
            try {
                srcData = paramStr.getBytes(ENCODING);
                // 加密后的数组
                byte[] cipherArray = encrypt_Ecb_Padding(keyData, srcData);
                // byte[]-->hexString
                cipherText = ByteUtils.toHexString(cipherArray);

            } catch (UnsupportedEncodingException e) {
                e.printStackTrace();
            } catch (Exception e) {
                e.printStackTrace();
            }

//            Long b = System.currentTimeMillis() - a;
//            System.out.println("time:" + b);
            return ENCRYPT_FLAG + cipherText;

        }
        else
        {
            return paramStr;
        }


    }

    /**
     * 加密模式之Ecb
     * @explain
     * @param key
     * @param data
     * @return
     * @throws Exception
     */
    public static byte[] encrypt_Ecb_Padding(byte[] key, byte[] data) throws Exception {
        Cipher cipher = generateEcbCipher(ALGORITHM_NAME_ECB_PADDING, Cipher.ENCRYPT_MODE, key);
        return cipher.doFinal(data);
    }

    /**
     * sm4解密
     * @explain 解密模式：采用ECB
     * //@param hexKey
     *            16进制密钥
     * @param cipherText
     *            16进制的加密字符串（忽略大小写）
     * @return 解密后的字符串
     * @throws Exception
     */
    public static String decryptEcb(String cipherText) {

        // 判断是否是加密字符串并截取密文
        if (cipherText != null && !"".equals(cipherText.trim()) && cipherText.startsWith(ENCRYPT_FLAG))
        {
            // 用于接收解密后的字符串
            String decryptStr = "";
            // hexString-->byte[]
            byte[] keyData = ByteUtils.fromHexString(KEY);
            cipherText = cipherText.substring(ENCRYPT_FLAG.length());
            // hexString-->byte[]
            byte[] cipherData = ByteUtils.fromHexString(cipherText);
            // 解密
            byte[] srcData = new byte[0];
            try {
                srcData = decrypt_Ecb_Padding(keyData, cipherData);
                // byte[]-->String
                decryptStr = new String(srcData, ENCODING);
            } catch (Exception e) {
                e.printStackTrace();
            }

            return decryptStr;
        }
        else
        {
            return cipherText;
        }

    }

    /**
     * 解密
     * @explain
     * @param key
     * @param cipherText
     * @return
     * @throws Exception
     */
    public static byte[] decrypt_Ecb_Padding(byte[] key, byte[] cipherText) throws Exception {
        Cipher cipher = generateEcbCipher(ALGORITHM_NAME_ECB_PADDING, Cipher.DECRYPT_MODE, key);
        return cipher.doFinal(cipherText);
    }

    /**
     * 校验加密前后的字符串是否为同一数据
     * @explain
     * @param hexKey
     *            16进制密钥（忽略大小写）
     * @param cipherText
     *            16进制加密后的字符串
     * @param paramStr
     *            加密前的字符串
     * @return 是否为同一数据
     * @throws Exception
     */
    public static boolean verifyEcb(String hexKey, String cipherText, String paramStr) throws Exception {
        // 用于接收校验结果
        boolean flag = false;
        // hexString-->byte[]
        byte[] keyData = ByteUtils.fromHexString(hexKey);
        // 将16进制字符串转换成数组
        byte[] cipherData = ByteUtils.fromHexString(cipherText);
        // 解密
        byte[] decryptData = decrypt_Ecb_Padding(keyData, cipherData);
        // 将原字符串转换成byte[]
        byte[] srcData = paramStr.getBytes(ENCODING);
        // 判断2个数组是否一致
        flag = Arrays.equals(decryptData, srcData);
        return flag;
    }

    public static void main(String[] args) {
        try {
//            String json = "{\"name\":\"Marydon\",\"website\":\"http://www.cnblogs.com/Marydon20170307\"}";
//            String json = "18512561372111111X";
            String json = "13344444444";
            System.out.println("明文长度:" + json.length());
            // 自定义的32位16进制密钥
            String key = "4BF601E10C6D4DF3A53F67647991C6F0";
            System.out.println("key长度:" + key.length());
            // 加密
            String cipher = Sm4Util.encryptEcb(json);
            System.out.println("密文:" + cipher);
            System.out.println("密文长度:" + cipher.length());
//            System.out.println(Sm4Util.verifyEcb(key, cipher, json));// true
            // 解密
            json = Sm4Util.decryptEcb(cipher);
            System.out.println("解密后:" + json);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }


}
